Fred, thanks for your latest comments. I drove the mercedes this morning for about 25 miles. When I got home, I located the source of the burning oil smoke near the EGR valve on the exhaust manifold side. This time the smoke is clear color type and not blue smoke. Also, I checked the exhaust tail pipe and there is no smoke coming out there, either. I can't exactly pinpoint the location but it appears to be on the tubing or pipe connected to the EGR valve. After starting the engine again, the smoke went away and no burning smell. I will keep monitoring on this issue and, if necessary, will report back on my findings.